The primary aim of this Phase I study is to evaluate the pharmacological dose-related effects of a newly developed contrast agent for use with MRI. Agents currently being used are available in doses of 0.1 to 0.3 mmol/kg. This new agent is a non-ionic, extracellular, linear gadolinium based chelate that will be tested in doses of 0.1, 0.3, and 0.5 mmol/kg. Subjects will be patients with known brain, spine, and/or liver disease, and were chosen to be representative of the type of patient for which contrast MRI is currently being used. This study was completed in September, 1997.